Below is my setup :

I Can run @ 200 MHz Blck using 18x multiplier @ 3.6GHz no issues what so ever , prime stable , Intel Burn test stable .
But Cant touch 4.00 GHz , ie 20 x multiplier @ 4.00 GHz. Tried CPU voltages upto 1.4V I keep running into 124 BSOD when i start prime.
I have also tried uping my QPI from 1.335 to .1.55V and the result is the same BSOD.

Do you guys think my CPU is maxed out and doesnt like 4.00 GHz and beyond? My Temps on Load are between 65 - 70 C so looks like I have sufficient cooling.

Intel Core7 920. C0 stepping @ 3.6 GHz @ 200 MHz Bclk , 1.28V CPU , 1.335V QPI/VTT and 1.68V Memory
Gigabyte GA-X58-extreme (BIOS v.F8e)
Cooler Master HAF 932
PSU: Tagan 700 watts
Cooler Master V8 CPU cooler
RAM: OCZ3P1600LV6G - 6GB Triple Channel - 1600 Mhz @ 7,7,7,21
GPU:Zotac GTX275
HDD:1TB Segate 7200.12 & 1TB WD caviar Black edition
Os: 64bit Windows 7 , OSX Leopard 10.5.7 & Vista 32 Bit SP2
Mon : Asus 26inch @ 1920 x 1200